Devices conducting network communications over wireless links are becoming increasing popular. Wireless links typically transmit data over radio frequency channels but may operate over other carrier frequency ranges, such as infrared. Most radio frequency (“RF”) based wireless networks are designed to operate in two basic modes: the infrastructure mode and the peer-to-peer or ad hoc mode.
In the infrastructure (“IS”) mode, which is also sometimes referred to as the managed network mode, each wireless network node communicates with the other nodes in the network through an access point (“AP”) node of the IS network. The packets directed by an IS node to another IS node carry the AP's Media Access Control (“MAC”) address in the link layer header. The access point functions as a bridge, repeater, gateway, and firewall between wireless nodes and wired nodes of the network. The access point also apportions bandwidth of the communication channel to the wireless IS nodes to ensure the quality of the communications.
In the ad hoc (“AH”) mode, a wireless node communicates directly, i.e., in a peer-to-peer fashion, with other nodes within its RF range without going through an intermediate node such as the access point of the IS network. Ad hoc wireless network connections are useful when close-by users want to communicate with each other in places where no IS network exists, or when they fail to be authorized by the access point of an existing IS network.
Conventionally, there is no interaction between nodes in an infrastructure network and nodes in an ad hoc network even if they have overlapping transmission ranges. There are, however, many situations where the ability for a wireless device to operate in both the ad-hoc and infrastructure networks may be desirable. For instance, in one scenario, employees from company A conduct a business meeting at company B with an employee of company B. Company B has an internal corporate network that supports an infrastructure wireless network. The visitors need to share electronic information such as documents, presentations, and data with their host. This can be done if the visitors can use their laptop computers to communicate wirelessly with the laptop computer of company B. For security concerns, the visitors are not allowed access to company B's internal network. Thus, the laptop computers of the visitors cannot operate as nodes of company B's infrastructure network.
One solution is that the visitors' computers can form an ad hoc wireless network with the host's computer. This solution requires the host's computer to operate as an ad hoc node. This, however, can pose a problem to the computer of the host, i.e., company B's employee, if he intends to have his computer connected wirelessly to the internal network of company B so that he can retrieve data for sharing with the visitors. Traditionally, nodes operating in the IS mode cannot talk to any node operating in the AH mode, and vice versa. This is because the IS nodes talk through the AP while AH nodes talk directly among themselves, and the AP does not know about AH nodes. To function as a node of the ad hoc network, the host's computer has to disconnect and log off from the infrastructure network. This is done by an administrative program that manages the wireless configuration of the card on the computer by telling the wireless driver to disassociate from the AP and enter the ad hoc mode. When operating in the ad hoc mode, the host's computer will not be able to access the IS network. When it later wants to function as a node of the infrastructure network, it then has to exit the ad hoc network and reconnect to the infrastructure network.